Method and device for security MBS communication in wireless communication system

This application is a National Phase Entry of PCT International Application No. PCT/KR2021/003859, which was filed on Mar. 29, 2021, and claims priority to Korean Patent Application Nos. 10-2020-0037803, which was filed on Mar. 27, 2020, the entire content of each of which is incorporated herein by reference.

The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for security multicast and broadcast service (MBS) communication in a wireless communication system.

To meet the increasing demand with respect to wireless data traffic after the commercialization of 4th generation (4G) communication systems, efforts have been made to develop 5th generation (5G) or pre-5G communication systems. For this reason, 5G or pre-5G communication systems are called ‘beyond 4G network’ communication systems or ‘post Long Term Evolution (post-LTE)’ systems. To achieve high data rates, implementation of 5G communication systems in an ultra-high frequency or millimeter-wave (mmWave) band (e.g., a 60 GHz (80 GHz) band) is being considered. To reduce path loss of radio waves and increase a transmission distance of radio waves in the ultra-high frequency band for 5G communication systems, various technologies such as beamforming, massive multiple-input and multiple-output (massive MIMO), full-dimension MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antennas are being studied. To improve system networks for 5G communication systems, various technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving networks, cooperative communication, coordinated multi-points (CoMP), and received-interference cancellation have been developed. In addition, for 5G communication systems, advanced coding modulation (ACM) technologies such as hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC), and advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), have been developed.

The Internet has evolved from a human-based connection network, where humans create and consume information, to the Internet of things (IoT), where distributed elements such as objects exchange information with each other to process the information. Internet of everything (IoE) technology has emerged, in which the IoT technology is combined with, for example, technology for processing big data through connection with a cloud server or the like. To implement the IoT, various technological elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required and, in recent years, technologies related to sensor networks for connecting objects, machine-to-machine (M2M) communication, and machine-type communication (MTC) have been studied. In the IoT environment, intelligent Internet technology (IT) services may be provided to collect and analyze data obtained from connected objects to create new value in human life. As existing information technology (IT) and various industries converge and combine with each other, the IoT may be applied to various fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, health care, smart home appliances, and advanced medical services.

Various attempts are being made to apply 5G communication systems to the IoT network. For example, technologies related to sensor networks, M2M communication, and MTC are being implemented by using 5G communication technology including beamforming, MIMO, and array antennas. Application of a cloud RAN as the above-described big data processing technology may be an example of convergence of 5G communication technology and IoT technology.

As various services may be provided according to the above features and the development of wireless communication systems, methods for seamlessly providing services related to multicast and broadcast are particularly required.

Described embodiments provide an apparatus and method capable of effectively supporting a service in a mobile communication system.

According to an embodiment of the present disclosure, an operating method of a terminal in a wireless communication system includes receiving configuration information to be applied to multicast and broadcast service (MBS) data from a base station, and receiving the MBS data based on the configuration information, wherein the configuration information is for configuring an initial value of a state variable corresponding to the MBS data.

The receiving of the configuration information from the base station may include receiving the configuration information while the MBS data is broadcast or multicast from the base station.

The configuration information may include at least one of an RX_DELIV value, an RX_NEXT value, a COUNT value, or a hyper frame number (HFN) value.

The operating method may further include identifying an HFN value of a first-received MBS data packet among the MBS data based on the RX_DELIV value or the RX_NEXT value.

The operating method may further include identifying, based on the HFN value, a COUNT value of a first-received MBS data packet among the MBS data.

According to an embodiment of the present disclosure, an operating method of a base station in a wireless communication system includes broadcasting or multicasting multicast and broadcast service (MBS) data to a terminal, and transmitting, to the terminal, configuration information to be applied to a first MBS data packet received by the terminal among the MBS data, wherein the configuration information is for configuring an initial value of a state variable corresponding to the first MBS data packet.

The configuration information may include at least one of an RX_DELIV value, an RX_NEXT value, a COUNT value, or a hyper frame number (HFN) value.

The initial value may be determined by an HFN value identified based on the RX_DELIV value or the RX_NEXT value.

The initial value may be determined by a COUNT value identified based on the HFN value.

According to an embodiment of the present disclosure, a terminal in a wireless communication system includes a transceiver, and at least one processor coupled with the transceiver, wherein the at least one processor is configured to receive configuration information to be applied to multicast and broadcast service (MBS) data from a base station, and receive the MBS data based on the configuration information, wherein the configuration information is for configuring an initial value of a state variable corresponding to the MBS data.

The at least one processor may be configured to receive the configuration information while the MBS data is broadcast or multicast from the base station.

The configuration information may include at least one of an RX_DELIV value, an RX_NEXT value, a COUNT value, or a hyper frame number (HFN) value.

The at least one processor may be configured to identify an HFN value of a first-received MBS data packet among the MBS data based on the RX_DELIV value or the RX_NEXT value.

The at least one processor may be configured to identify, based on the HFN value, a COUNT value of a first-received MBS data packet among the MBS data.

According to an embodiment of the present disclosure, a base station in a wireless communication system includes a transceiver, and at least one processor coupled with the transceiver, wherein the at least one processor is configured to broadcast or multicast multicast and broadcast service (MBS) data to a terminal, and transmit, to the terminal, configuration information to be applied to a first MBS data packet received by the terminal among the MBS data, wherein the configuration information is for configuring an initial value of a state variable corresponding to the first MBS data packet.

Hereinafter, operation principles of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, detailed descriptions of well-known functions or configurations will be omitted because they would unnecessarily obscure the subject matters of the present disclosure. Also, terms described below may be terms defined considering functions in the present disclosure and may vary according to users' or operators' intentions or practices. Therefore, the definition thereof should be made based on the content throughout the specification.

For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically illustrated. Also, the size of each component may not completely reflect the actual size thereof. In the drawings, the same or corresponding elements may be given the same reference numerals.

The advantages and features of the present disclosure and the accomplishing methods thereof will become apparent from the embodiments of the present disclosure described below in detail with reference to the accompanying drawings. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments of the present disclosure described below; rather, the embodiments are provided to complete the present disclosure and fully convey the scope of the present disclosure to those of ordinary skill in the art and the present disclosure will be defined only by the scope of the claims. Throughout the specification, like reference numerals may denote like elements.

It will be understood that each block of process flowchart diagrams and combinations of flowchart diagrams may be performed by computer program instructions. Because these computer program instructions may be mounted on a processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, the instructions executed through a processor of a computer or other programmable data processing equipment may generate a means of performing the functions described in the flowchart block(s). Because these computer program instructions may be stored in a computer-executable or computer-readable memory that may be directed to a computer or other programmable data processing equipment to implement a function in a particular manner, the instructions stored in the computer-executable or computer-readable memory may also produce a production item containing an instruction means of performing the functions described in the flowchart block(s). Because the computer program instructions may also be mounted on a computer or other programmable data processing equipment, the instructions performing a series of operations on the computer or other programmable data processing equipment to generate a computer-implemented process to perform the computer or other programmable data processing equipment may also provide operations for executing the functions described in the flowchart block(s).

Also, each block may represent a portion of a module, segment, or code including one or more executable instructions for executing one or more specified logical functions. Also, it should be noted that the functions mentioned in the blocks may also occur in a different order in some alternative implementation examples. For example, two blocks illustrated in succession may actually be performed substantially at the same time or may sometimes be performed in the opposite order depending on the corresponding function.

In this case, the term “unit” used in the present embodiments may refer to a software component or a hardware component such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) and the “unit” may perform certain functions. However, the “unit” is not limited to software or hardware. The “unit” may be configured to be in an addressable storage medium or may be configured to operate one or more processors. Thus, as an example, the “unit” may include components such as software components, object-oriented software components, class components, and task components and may include processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. A function provided by the components and “units” may be associated with the smaller number of components and “units” or may be further divided into additional components and “units”. In addition, the components and “units” may be implemented to operate one or more central processing units (CPUs) in a device or a security multimedia card. Also, in embodiments, the “unit” may include one or more processors.

In the following description of the present disclosure, detailed descriptions of well-known functions or configurations will be omitted because they would unnecessarily obscure the subject matters of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

In the following description, terms for identifying access nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, and the like are used for convenience of descriptions. Thus, the present disclosure is not limited to the terms used below and other terms referring to objects having equivalent technical meanings may be used.

Hereinafter, a base station may be an agent performing terminal resource allocation and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a radio access unit, a base station controller, or a node on a network. Examples of the terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Also, the term “terminal” may refer to other wireless communication devices in addition to mobile phones, NB-IoT devices, and sensors. However, the base station and the terminal are not limited thereto.

Hereinafter, for convenience of descriptions, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standards and/or 3rd Generation Partnership Project New Radio (NR). However, the present disclosure is not limited to those terms and names and may be equally applied to systems according to other standards. In the present disclosure, eNB may be used interchangeably with gNB for convenience of descriptions. That is, a base station described as an eNB may represent a gNB.

Particularly, the present disclosure may be applied to 3GPP NR (5G mobile communication standards). Also, the present disclosure may be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security, and safety-related services) based on 5G communication technology and IoT technology. In the present disclosure, eNB may be used interchangeably with gNB for convenience of descriptions. That is, a base station described as an eNB may represent a gNB. Also, the term “terminal” may refer to other wireless communication devices in addition to mobile phones, NB-IoT devices, and sensors.

Wireless communication systems providing voice-based services are being developed to broadband wireless communication systems providing high-speed and high-quality packet data services according to communication standards such as high speed packet access (HSPA), long term evolution (LTE) or evolved universal terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), and LTE-Pro of 3GPP, high rate packet data (HRPD) and ultra mobile broadband (UMB) of 3GPP2, and 802.16e of the Institute of Electrical and Electronics Engineers (IEEE).

As a representative example of the broadband wireless communication systems, LTE systems employ orthogonal frequency division multiplexing (OFDM) for a downlink (DL) and employs single carrier-frequency division multiple access (SC-FDMA) for an uplink (UL). The uplink may refer to a radio link for transmitting data or a control signal from a terminal (e.g., a user equipment (UE) or a mobile station (MS)) to a base station (e.g., an eNode B (eNB) or a base station (BS)), and the downlink may refer to a radio link for transmitting data or a control signal from the base station to the terminal. The above-described multiple access schemes distinguish between data or control information of different users by allocating time-frequency resources for the data or control information of the users not to overlap each other, that is, to achieve orthogonality therebetween.

As post-LTE systems, 5G systems may have to support services capable of simultaneously satisfying various requirements because they may have to freely reflect various requirements of users, service providers, and the like. Services considered for the 5G systems may include enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliability low-latency communication (URLLC) services.

According to an embodiment, the eMBB may aim to provide an improved data rate than the data rate supported by the existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, the eMBB should be able to provide a peak data rate of 20 Gbps in a downlink and a peak data rate of 10 Gbps in an uplink from the viewpoint of a base station. Also, the 5G communication system may have to provide an increased user-perceived data rate of a terminal while providing a peak data rate. In order to satisfy this requirement, the 5G communication system may require the improvement of various transmission/reception technologies including a more improved Multi Input Multi Output (MIMO) transmission technology. Also, the 5G communication system may satisfy a required data rate by using a frequency bandwidth wider than 20 MHz in the 3 GHz to 6 GHz or 6 GHz or more frequency band while transmitting signals by using a transmission bandwidth of up to 20 MHz in the 2 GHz band used in the current LTE.

Simultaneously, the mMTC is being considered to support application services such as Internet of Thing (IoT) in 5G communication systems. In order to efficiently provide the IoT, the mMTC may require the support for access of large terminals in a cell, improved terminal coverage, improved battery time, reduced terminal cost, and the like. Because the IoT is attached to various sensors and various devices to provide a communication function, it should be able to support a large number of terminals (e.g., 1,000,000 terminals/km) in a cell. Also, because a terminal supporting the mMTC is likely to be located in a shadow area failing to be covered by the cell, such as the basement of a building, due to the characteristics of the service, it may require wider coverage than other services provided by the 5G communication systems. The terminal supporting the mMTC should be configured as a low-cost terminal and may require a very long battery life time of about 10 years to about 15 years because it is difficult to frequently replace the battery of the terminal.

Lastly, the URLLC may be used in services for remote control of robots or machinery, industrial automation, unmanned aerial vehicles, remote health care, emergency alerts, and the like, as cellular-based wireless communication services used for mission-critical purposes. Thus, the communication provided by the URLLC may have to provide very low latency (ultra-low latency) and very high reliability (ultra-high reliability). For example, a service supporting the URLLC should satisfy an air interface latency of less than 0.5 milliseconds and simultaneously may have a requirement for a packet error rate of 10-5 or less. Thus, for the service supporting the URLLC, the 5G system should provide a smaller transmit time interval (TTI) than other services and simultaneously may have a design requirement for allocating wide resources in frequency bands in order to secure the reliability of communication links.

The above three services of eMBB, URLLC, and mMTC considered in the 5G communication systems may be multiplexed and transmitted in one system. In this case, different transmission/reception techniques and transmission/reception parameters may be used between services in order to satisfy different requirements of the respective services. However, the above-described mMTC, URLLC, and eMBB are merely examples of different service types, and the service types to which the present disclosure is applied are not limited thereto.

Also, although embodiments of the present disclosure will be described below by using an LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) as an example, the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel forms. Also, the embodiments of the present disclosure may also be applied to other communication systems through some modifications without departing from the scope of the present disclosure by the judgment of those of ordinary skill in the art.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

is a diagram illustrating an operating method of MBS communication according to an embodiment of the present disclosure. Multicast and broadcast service (MBS) communication may refer to a method by which one transmitting apparatus communicates with several receiving apparatuses in a mobile communication system. Here, the transmitting apparatus may be a base station, and each receiving apparatus may be a terminal. However, the present disclosure is not limited thereto, and the transmitting apparatus may be a terminal.

illustrates an example of MBS communication in which a base station (gNB)is a transmitting apparatus and terminals,,, andare receiving apparatuses. The MBS communication may be a broadcast for a plurality of unspecified receiving apparatuses or may be a multicast for a plurality of particular receiving apparatuses. When communication is performed in a multicast manner, the base station may configure only a particular terminal to receive a corresponding multicast packet. For this purpose, a set of terminals to perform a particular multicast communication may be configured and will be referred to as a multicast groupin the embodiment of.

By being allocated the same group-radio network temporary identity (G-RNTI) from the base station, the terminals,, andin the multicast groupmay receive data allocated for the G-RNTI. In the embodiment of, it is assumed that a terminal, a terminal, and a terminalare configured as one multicast groupand allocated the G-RNTI to receive data from the base stationin a multicast manner. Because a terminalis not included in the multicast group, the terminalmay not be allocated the G-RNTI and accordingly the terminalmay not receive the data that the terminal, the terminal, and the terminalreceive from the base station.

One or more multicast groups may be configured in the coverage of the base station, and each multicast group may be identified by the G-RNTI. One terminal may be allocated one or more G-RNTIs from the base station. Not only in the connected mode (RRC CONNECTED MODE) but also in the idle mode (RRC IDLE MODE) or the inactive mode (RRC INACTIVE MODE), the terminal may receive multicast data by using the G-RNTI value allocated in the connected mode. The G-RNTI may be configured in the terminal by being included in at least one of RRC reconfiguration, RRC establishment (setup), and RRC reestablishment messages that the terminal may receive in the connected mode. However, the present disclosure is not limited thereto, and the G-RNTI may be transmitted from the base station by being included in a system information block (SIB) as a G-RNTI value that the terminal may receive. The terminal configured with the G-RNTI value according to one or more of the various methods described above may apply the G-RNTI value after being configured with the G-RNTI value.

is a diagram illustrating an operation in which a terminal receives data for MBS communication from the middle of transmission data, according to an embodiment of the present disclosure. The MBS communication may be a communication method by which a plurality of terminals receive the same data from a base station. Whether a terminal will receive data for a particular MBS communication may be determined according to whether the terminal is interested in data of the MBS communication. However, all terminals may not receive the data of the MBS communication simultaneously. For example, by establishing an RRC connection with the base stationat a time later than when other terminals receive information about MBS communication from the base station, a terminalmay receive the information about the MBS communication later than the other terminals. In this case, the reception time of the terminalwith respect to data for MBS communication may be delayed. That is, there may be a case in which the terminalreceives data transmitted from the base stationfor MBS communication, from the middle without receiving the data from the beginning. As another example, due to the mobility of the terminal, the terminalmay perform handover to the coverage of a base station other than the base station. In this case, in the coverage of the base station, because the reception time of the data for the MBS communication desired by the terminalmay be after the handover, the terminalmay receive the data from a time different from the time when another terminal receives the data for the MBS communication from the base station. For example, referring to, the base stationtransmitting data of MBS communication may transmit data associated with a certain MBS communication, and the terminalattempting to receive data for MBS communication may not receive the data transmitted by the base station from the beginning due to various reasons. Alternatively, the terminalmay perform data reception for MBS communication after obtaining reception information for MBS communication. This may mean that the packet may be received () from the middle of the sequence number in the packet data convergence protocol (PDCP) layer. Receiving the packet from the middle of the sequence number as such may mean that the existing unicast transmission/reception procedure of configuring the initial value of the sequence number as 0 may not be used. Particularly, when a security function such as ciphering and integrity protection should be performed, a COUNT value corresponding to a combination of a sequence number value and a hyper frame number (HFN) value should match with respect to the packet transmitted between the base stationas a transmitting apparatus and the terminalas a receiving apparatus. The present disclosure proposes a method of configuring an HFN value and a COUNT value of a packet between a base station and a terminal in order to perform a security function in MBS communication.

is a diagram illustrating a method of configuring RX_DELIV and RX_NEXT that are state variables of a PDCP layer. A receiving operation of the PDCP layer may be performed through a process of updating the value of a state variable representing the COUNT value of a packet. The main state variables used in this case may include RX_DELIV and RX_NEXT. RX_DELIV may represent the COUNT value of a packet with the smallest COUNT value among the packets that have not been transmitted to the upper layer of the PDCP layer but are still waiting for reception in the PDCP layer. RX_NEXT may be the COUNT value of a packet expected to be received in the next PDCP layer and may be configured as a value obtained by adding 1 to the greatest COUNT value among the COUNT values of the packets received up to now.

illustrates an example in which RX_DELIV and RX_NEXT are configured. It is assumed that packets corresponding to COUNT values 35, 36, and 40 have been received at the time of. However, it is assumed that packets corresponding to COUNT values 37, 38, 39, 41, 42, and higher values have not been received. In this case, the PDCP layer may sequentially transmit the received packets up to COUNT 36 to the upper layer. However, in order to wait for the packets corresponding to the COUNT values 37, 38, and 39, which are non-received packets with COUNT values less than 40, the packet corresponding to the COUNT value 40, which has been received, may be queued in a PDCP reception buffer without being transmitted to the upper layer. In this case, RX_NEXTmay be configured as 41 that is a value obtained by adding 1 to the COUNT value of the packets received up to now. This may be because the packet corresponding to the COUNT value of 41 is expected to arrive at the next PDCP layer. Also, 37 having the smallest COUNT value among the packets that have not been received up to now may be configured as RX_DELIV. That the RX_DELIV value and the RX_NEXT value are different may indicate that there is a packet currently stored in the PDCP reception buffer and the PDCP layer is waiting for a packet having a smaller COUNT value than the stored packet.illustrates a situation in which the PDCP layer should wait for the reception of the packets corresponding to the COUNT values 37, 38, and 39 because the packet corresponding to COUNT 40 has arrived but the packets corresponding to COUNT 37, 38, and 39 have not yet arrived. For this purpose, the PDCP layer may start a reordering timer, configure the RX_NEXT value as an RX_REORD state variable, and wait for the reception of a packet less than or equal to the RX_REORD value during the reordering timer period. In the case of the terminal performing data reception for MBS communication, it may be necessary to determine which RX_DELIV and RX_NEXT values to use when starting MBS communication. For example, the terminal may need to determine which RX_DELIV and RX_NEXT values to use in order to prevent an unintentional packet loss or prevent a delay time increase due to packet reordering.

is a diagram illustrating an operation in which a terminal receives data for MBS communication from the middle of transmission data, according to an embodiment of the present disclosure. The MBS communication may be a communication method by which a plurality of terminals receive the same data from a base station. Whether a terminal will receive data for a particular MBS communication may be determined according to whether the terminal is interested in data of the MBS communication. However, all terminals may not receive the data of the MBS communication simultaneously. For example, by establishing an RRC connection with the base stationat a time later than when other terminals receive information about MBS communication from the base station, a terminalmay receive the information about the MBS communication later than the other terminals. In this case, the reception time of the terminalwith respect to data for MBS communication may be delayed. That is, there may be a case in which the terminalreceives data transmitted from the base stationfor MBS communication, from the middle without receiving the data from the beginning. As another example, due to the mobility of the terminal, the terminalmay perform handover to the coverage of a base station other than the base station. In this case, in the coverage of the base station, because the reception time of the data for the MBS communication desired by the terminalmay be after the handover, the terminalmay receive the data from a time different from the time when another terminal receives the data for the MBS communication from the base station. For example, referring to, the base stationtransmitting data of MBS communication may transmit data about a certain MBS communication, and the terminalattempting to receive data for MBS communication may not receive the data transmitted by the base station from the beginning due to various reasons. Alternatively, the terminalmay perform data reception for MBS communication after obtaining reception information for MBS communication. This may mean that the packet may be received () from the middle of the sequence number in the packet data convergence protocol (PDCP) layer. Receiving the packet from the middle of the sequence number as such may mean that the existing unicast transmission/reception procedure of configuring the initial value of the sequence number as 0 may not be used. Particularly, when a security function such as ciphering and integrity protection should be performed, a COUNT value corresponding to a combination of a sequence number value and a hyper frame number (HFN) value should match with respect to the packet transmitted between the base stationas a transmitting apparatus and the terminalas a receiving apparatus.